Chapter 12. Intellectual Disability (Mental Retardation)

Karen Toth, Ph.D.; Bryan H. King, M.D.
DOI: 10.1176/appi.books.9781585623921.455286



In 1992, the American Association on Mental Retardation (AAMR), now the American Association on Intellectual Disability and Developmental Disabilities (AAIDD), proposed a new classification system for intellectual disability based on intensity of supports needed (intermittent, limited, extensive, and pervasive) as opposed to the traditional system of classification by IQ score (mild, moderate, severe, and profound). The current definition (not yet reflected in the current version of the Diagnostic and Statistical Manual of Mental Disorders [DSM-IV; American Psychiatric Association 1994] and its text revision, DSM-IV-TR [American Psychiatric Association 2000]) recognizes that intellectual disability is characterized by genuine impairments, but it also reflects the idea that these impairments are strongly influenced by the individual's interaction with the environment. The new definition emphasizes strengths rather than limitations.

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TABLE 12–1. Summary of DSM-IV-TR diagnostic criteria and severity classifications for mental retardation
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TABLE 12–2. Standardized tests of intelligence for use with children with intellectual disabilities
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TABLE 12–3. Standardized measures of development for infants and toddlers
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TABLE 12–4. Measures of adaptive functioning
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TABLE 12–5. Resources for families and individuals with intellectual disabilities


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In 1992, the American Association on Mental Retardation (AAMR), now the American Association on Intellectual Disability and Developmental Disabilities (AAIDD), proposed a new classification system for intellectual disability based on intensity of supports needed as opposed to the traditional system of classification by IQ score. For the new proposed classification, where would someone be classified if he or she requires additional support to navigate through everyday situations?
Which of the following predisposing factors is associated with the highest percentage of cases of intellectual disability?
Which of the following risk factors for intellectual disability of unknown etiology is the strongest predictor of disability?
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